Medical needles are used in clinical procedures to pierce tissue in order to deliver fluids containing pharmaceutical compounds subcutaneously, and also to gather tissues, cells and/or bodily fluid for diagnostics. In certain procedures, it is desirable to insert the needle tip to a specific location. For example, in some anaesthetic procedures, anaesthetic may need to be delivered beside a nerve.
Misplacement of the needle and needle related injury are a significant concern to the proceduralist and patient. In certain procedures it is particularly important to avoid piercing or damaging nerves, veins, arteries, and other organs/entities during insertion of the needle. For these reasons, proceduralists use many techniques for identifying the location of the needle tip.
It is now relatively common to use ultrasound to confirm needle positioning during procedures. This involves the use of ultrasound waves to observe, in real time, the position of the needle tip. Ultrasound waves are introduced by a transducer. The ultrasound waves received by the transducer are used generate an image.
The ultrasound waves are readily reflected by changes in material density. In this context, changes between layers of tissue, tissue and nerve fibres, and medical equipment (including needles) and tissue are all capable of reflecting ultrasound waves. An ultrasound wave is strongly reflected at the interface of the two materials, such as a needle/tissue interface.
Where the needle/tissue interface is perpendicular to ultrasound waves emitted from a transducer, the waves can be reflected directly back to the transducer. This produces a very clear ultrasound image of the needle within the tissue. However, in most cases the needle is at an oblique angle to the transducer, so the needle/tissue interface is oblique to the emitted ultrasound wave. This results in the ultrasound waves being reflected away from the transducer, which decreases the visibility of the needle in the ultrasound image. This problem is exacerbated with steep angles of insertion; that is, as the needle approaches the parallel to the emitted ultrasound waves.
In some cases, the needle can only be seen in the ultrasound image as a silhouette in the surrounding tissue. In other words, the needle location can be determined in the ultrasound image by an echogenic shadow created by the needle.
It is known to provide medical needles for insertion into a patient that have an ultrasonic reflector formed in the outer surface for reflecting ultrasound waves back towards the source. It is also known to provide a number of such reflectors dispersed over the surface of a medical needle.
The present invention seeks to provide a medical needle with increased visibility in ultrasound guided procedures.